Paris, Christmas 2021. After a heart attack, Mathias Taillefer wakes up in hospital with a stranger at his bedside. The mysterious girl reveals herself to be Louise Collange, a volunteer who has come to play the cello for patients. When she finds out Mathias is a cop, she asks him to take charge of a very special case. Her mother, a former ballerina at the Paris Opera Ballet, died last year after falling from her balcony, and Louise has a hunch she was pushed. Though hesitant at first, Mathias agrees to help her, sending them both headfirst into a deadly chain of events. And at the centre of it all, a woman named Angélique, whose angelic intentions may not be all they seem.